Of course, the above I've suggested are just some of the options from known lines. You never know, there may be a G.I. Joe scale line that isn't really well know but is over produced that could have parts or even a full body in a suit that you can use. Either way, it's going to take some work to find the right body/parts and confirm the correct scale to make such a figure.

For the hair, there is a noticeable difference between Alan's hair circa 1982 and TRON's hair circa 1989.

TRON circa 1989:
Picture 1Picture 2Picture 3 (as depicted in the game, in which the hairstyle looks more like the 1982 Alan Bradley hair. However, you can see the noticeable difference in the hairstyle, even more so when you compare it to the comic, so take this one picture with a grain of salt).

Alan Bradley circa 1989:
I wasn't able to find any screencaps of where you see Alan from the news report after Kevin Flynn disappears, so I had to make my own. Here it is. As you can see, his hair is a different from how he had it in 1982.

Next, I need to secure The Miz's neck to the inside of Sam's body. I'm thinking of using a 2-part epoxy or something. Oh, The Miz also donated his left hand to Sam. They use the same type of joint to plug into the wrist, but The Miz has a cool swivel joint within the hand and actually grips the identity disk a lot better than Sam does.

His hair also needs some blonde or light brown highlights but I'm not going to bother sculpting or reshaping the hair as I think hair style is close enough for this character.

Finally, I hope to salvage what is left of Sam's helmet in order to give him a disk battle face shield that can simply slip over the new head.
I'm really happy with the results so far!